The present invention relates to a method of manufacturing stators for electrical machines or the like and an apparatus employed therefor, and, more particularly, to a method of winding electrical coils to be inserted into slots or grooves formed in stators and automatically inserting the wound coils into the grooves of the stator cores by inserting jigs and an apparatus for effecting said method in an efficient manner.
Conventionally, for manufacturing stators of electrical machines and the like, there has been proposed, for example, in U.S. Pat. No. 3,828,830, an apparatus as illustrated in FIG. 1 which generally includes a coil winding device 501, a coil inserting device 502 for inserting wound coils into grooves of stator cores by a coil inserting jig 503, and a rotary table 504 having two coil inserting jigs 503 provided thereon. The coil winding device 501 is equipped with two winding reels 505 disposed at opposite ends of an arm 506, one of which winding reels 505 is arranged in position above the coil inserting jig 503. The other of the winding reels 505 is located above a flyer 507 which winds electrical wires onto the winding reel 505 for producing electrical coils, while the arm 506 is arranged to be rotatable about a shaft 508. By the above arrangement, in the coil winding device 501, the coils produced on the outer periphery of the reel 505 by winding the electrical wires onto said reel 505 by the flyer 507 are brought above the coil inserting jig 503 through rotation of the arm 506. The coils thus preliminarily wound are transferred onto the coil inserting jig 503 as the coil inserting jig 503 descends. Upon completion of transfer of the coils wound around the winding reel 505 onto the coil inserting jig 503, the reel 505 ascends, and is has another coil wound thereon by the flyer 507 after rotation of the arm 506 about the shaft 508. Meanwhile, the particular coil inserting jig 503 which has received the wound coils from the winding reel 505 is transferred to the coil inserting device 502 through rotation of the rotary table 504, with an empty stator core being placed on the coil inserting jig 503, and the coil is inserted into the grooves of the stator core by an extractor (not shown) moving in the direction of the axis of the stator core.
The known apparatus of the rotary table type as described above, however, has disadvantages as follows.
(1) There tends to be a difference between the tact time for the steps from the coil winding to the transfer of the coils onto the inserting jig and the tact time for inserting the wound coils and insulating material into the stator core grooves, thus resulting in an idle-time either at the coil winding device or coil inserting device. Such idle time for the conventional apparatuses currently commercially available is approximately 30 seconds, and further improvement with respect to such idle time is extremely difficult to achieve.
(2) In cases where one winding device disposed on the rotary table is out of order or replacement of the wire material for the coil is required, the whole apparatus must be shut down, with the production being undesirably suspended.
(3) The apparatus of the rotary table type as described in the foregoing can not efficiently cope with changes in production planning for manufacturing stators having different winding characteristics.
In order to overcome the disadvantages as described above, there has also been proposed, for example, in U.S. Pat. No. 3,691,606, another apparatus as shown in FIG. 2. The apparatus shown in FIG. 2 includes a guide track 509 composed of segments which can be added to each other in a length-wise direction, and constituted by a curved rail portion 509a and straight rail portion 509b to form a closed path, transport carriages 510 which move along the guide track 509 and can be arrested at individual production stations arranged along the guide rail 509, a coil winding device 511, and a coil inserting device 512, with the transport carriages 510 being provided with the coil inserting jigs 513. By the above arrangement, in the coil inserting jig 513 of the transport carriage 510 at the position A on the right-hand side of FIG. 2, the stator is inserted, with the coil being received in the stator core, and the stator core is subsequently withdrawn (not shown) from the inserting jig 513. The empty transport carriage 510 moves along the guide rail 509 to a winding station B equipped with the coil winding device 511. Coils equivalent to two poles preliminarily wound on a reel 514 by the coil winding device 511 are simultaneously received by the inserting jig 513 of the transport carriage 510. Subsequently, the transport carriage 510 moves to a stator core inserting station C located next to the winding station B, and after the stator core is inserted onto an upper portion of the coil inserting jig 513, the coil is inserted into the stator core at a coil inserting station D. Thereafter, the transport carriage 510 further moves to return to the original position at the station A. With specific reference to the dotted line portion in FIG. 2, coil winding stations B, C, E, F.sub.1 and F.sub.2, and H.sub.1 and H.sub.2 are equipped with winding devices for winding different types of coils. Owing to types of stator core manufacturing, the apparatus is constituted by a group of stations B, C, E, F.sub.1 and F.sub.2, and G on one hand, and another group of stations H.sub.1,H.sub.2 and K on the other hand, while each of the two groups of the stations is adapted to be operable independently. The stations F.sub.1 and F.sub.2 or H.sub.1 and H.sub.2 are winding stations for winding the same types of coils in parallel relation, which arrangement makes it possible to manufacture stators for electrical machines, for example, by inserting auxiliary coils into the stator cores at the stations B, E, F and G, and main coils at the stations H.sub.1, H.sub.2 and K.
The known arrangement as described above, however, also has drawbacks as noted below.
(1) Since a plurality of winding devices are arranged in series in a closed path, the whole apparatus is undesirably shut down if one winding device is stopped, for example, due to trouble for maintenance, for adjustments or for replacement of the winding material.
(2) Since the transport carriage is constructed to incorporate a driving source therein, the cost of the apparatus on the whole is increased.
(3) If the number of the winding devices initially installed is required to be increased later, installation of the additional devices is very difficult.
(4) Since a number of winding reels corresponding to the number of poles of the coil per one winding device are employed, much time and labor are required for replacement of winding reels, for example, following changes of types of electrical machines to be produced.
Accordingly, an essential object of the present invention is to provide a method of manufacturing stators of electrical machines or the like and an apparatus employed therefor in which, in a system having a plurality of winding devices arranged in a closed path for transporting a plurality of coil inserting jigs so as to reduce production time, the winding devices are arranged in parallel to each other to enable branching and recombining of paths of movement of the jigs in order to avoid production shut down of the entire production line in cases where transportation of coil inserting jigs is stopped due to troubles in the winding devices and replacement of winding materials, or during adjustments of the winding devices, with consequent increase of production efficiency over the entire production line.
Another important object of the present invention is to provide a method and an apparatus employed therefor as described above in which a process for cutting and shaping insulating material into pieces corresponding to the number of grooves of the stator core and a process for inserting the insulating material pieces and coils into the stator core are made independent of each other to improve the overall production efficiency, with substantial elimination of disadvantages inherent in the conventional arrangements wherein such processes are effected in one step, requiring a considerable time.
A further object of the present invention is to provide a method and apparatus employed therefor as described above in which the winding devices are adapted to wind coils having a plurality of poles on one winding reel to reduce the time required for changing-over of types of electrical machines to be produced in order to remove the drawbacks in the known arrangements wherein replacement of a plurality of winding reels must be made on a plurality of winding devices during such change-over of product types, with much time and labor required therefor.
A still further object of the present invention is to provide a method and apparatus employed therefor as described above in which coil inserting jigs of simple construction and low cost can be employed, thus making possible a large reduction in cost especially when many inserting jigs are employed, for eliminating the disadvantages in the conventional arrangements that known coil inserting jigs having the driving sources or motors incorporated therein and guided along the guide rail by stopping and running controls are not readily removable when out of order, with consequent high cost.
Another object of the present invention is to provide a method and an apparatus employed therefor as described above in which the tact time for inserting insulating material pieces into a guide housing is reduced, by inserting such insulating material pieces from several places, as compared with the conventional insulating material piece inserting device in which the insulating material pieces are inserted at one place, while the entire apparatus is not shut down in such a case, with only a certain reduction in efficiency, since such insulating material pieces are inserted from other portions into the guide housing even when one portion is out of order.
A still another object of the present invention is to provide a method and an apparatus employed therefor as described above in which inconvenience in the conventional methods and arrangements arising from the fact that carrying out of the coil inserting jigs from the coil winding device tends to be obstructed due to inclination of a pallet because of line pressure applied thereto is advantageously eliminated.
A further object of the present invention is to provide a method and an apparatus employed therefor as described above in which, by depressing stator cores by shifting of a stator core depressing plate in a direction parallel to the axial direction of an insulating material guide, it is possible to hold the stator cores in position irrespective of variations in the thicknesses of the stator cores without any deformation to the insulating material guide.
A still further object of the present invention is to provide an apparatus of the above described type which is accurate and stable in functioning, and which has a simple construction and consequent low cost.